1. Field of the Invention
This invention relates to improved processes for the separation of unsaponifiable substances from raw materials including residues and by-products of the processing of animal and vegetable products, preferably by means of high vacuum distillation/evaporation. The unsaponifiable substances produced include liposoluble vitamins and provitamins, growth factors, animal and vegetable hormones, and other valuable products. Saponifiable substances may also be isolated by hydrolyzing the residues obtained from distillation/evaporation to produce higher quality fatty acids and other organic acids and/or a mixture of the same
2. Description of the Related Art
The recovery of the unsaponifiable fraction of a raw material is of great commercial interest, due to the fact that, in many cases, the valuable products have beneficial properties such as vitamin activities (e.g. tocopherols (vitamin E), tocotrienols, carotenoids, vitamin A, vitamin K, vitamin D), cholesterol reducing properties (e.g. sterols, tocotrienols), anticarcinogenic properties (e.g. tocotrienols, sterols, lycopene, alphacarotene), use in biosynthesis (e.g. sterols for human hormone synthesis, vitamin D synthesis), and nutriceuticals. For instance, sterols can be used as a supplement in the diet of animals and humans as a means to lower cholesterol in the blood serum. There is also commercial interest in the use of sterols as emulsion stabilizers and/or viscosity modifiers, especially in cosmetic formulas. Moreover, tocopherols are another unsaponifiable that can be used as a dietary supplement and also has an important role in the cosmetic industry. Saponifiable components, such as fatty acids and rosin acids can also be isolated from tall oil and both, separately or mixed together, have commercial value and utility. Cholesterol can also be isolated as an unsaponifiable from a matrix that comes from animal based fatty acids, particularly found in the residue of the distillation of animal based fatty acids.
Most processes used nowadays to separate and concentrate unsaponifiable substances from residues and by-products of the processing of animal and vegetable products and other raw materials use solvents, taking advantage of the difference of solubility between unsaponifiable substances and the soap matrix. Some processes use the difference of volatility between volatile unsaponifiables and non-volatile fatty/rosin acids sodium or potassium salts or soaps to separate the compounds by means of high vacuum distillation/evaporation.
The solvents available at present are not sufficiently selective to obtain, through the current processes, a reasonable separation between the unsaponifiable components and the fatty acid, the rosin acid soaps. Due to this, it is often necessary to use more than one solvent, which in turn complicates and increases tremendously the cost of recovery and recycling of the same. Furthermore, solvents or solvent mixtures are used in very large proportions, when compared to the quantity of the material submitted for extraction and the solvents need additional processes for their removal and/or recycling in the extraction and pre-concentration process of the valuable products. The foregoing reasons make solvent-based processes harder and more expensive, resulting in a scarce and expensive final product.
In the case of separation by distillation, the difference between the boiling point of volatile products, such as unsaponifiable components, and the boiling point of the sodium and potassium organic acid soaps is so great that separation is theoretically possible at a high level of efficiency. However, a problem related to this separation technique is that the soaps have a very high melting point, close to the decomposition temperature of the sodium or potassium soaps (i.e. the sodium or potassium salts of fatty acids, rosin acids etc), and, when melted, these soaps form extremely viscous liquids. These two factors combine to make industrial handling difficult. Furthermore, while at the high temperature necessary to maintain their flow, these soaps are in permanent decomposition, compromising the separation output and the quality of the final product, as many of the unsaponifiable valuable products are heat sensitive.